U.S. patent application number 16/163999 was filed with the patent office on 2019-04-25 for silicone composition, a cured silicone rubber product and a power cable.
This patent application is currently assigned to Shin-Etsu Chemical Co., Ltd.. The applicant listed for this patent is Shin-Etsu Chemical Co., Ltd.. Invention is credited to Tatsuei HARA, Yoshiaki KOIKE, Kazuhiro OISHI.
Application Number | 20190119495 16/163999 |
Document ID | / |
Family ID | 63965148 |
Filed Date | 2019-04-25 |
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United States Patent
Application |
20190119495 |
Kind Code |
A1 |
HARA; Tatsuei ; et
al. |
April 25, 2019 |
SILICONE COMPOSITION, A CURED SILICONE RUBBER PRODUCT AND A POWER
CABLE
Abstract
The present invention provides a silicone composition comprising
components (A) to (F); (A) 100 parts by mass of a raw rubber-like,
at 25 degrees C., organopolysiloxane having at least two alkenyl
groups each bonded to a silicon atom; (B) 5 to 100 parts by mass of
silica powder having a specific surface area of 50 m.sup.2/g or
more; (C) platinum or a platinum compound in an amount of 1 to
1,000 ppm by mass as a platinum atom, relative to the mass of
component (A); (D) 0.01 to 5 parts by mass of a compound selected
from an organic silicon compound having a nitrogen-containing
organic group and an unsaturated hydrocarbon group, and
benzotriazole and a derivative thereof; (E) an addition reaction
curing agent other than said component (C), or an organic peroxide
in an effective amount to cure the composition, and (F) 0.01 to 5
parts by mass of an aromatic hydrocarbon group-containing
organopolysiloxane represented by the general formula (1) wherein a
proportion of the number of the monovalent aromatic hydrocarbon
group to the total number of the substituents R.sup.1, R.sup.2 and
R.sup.3 is 41% or more and less than 46%.
Inventors: |
HARA; Tatsuei; (Annaka-shi,
JP) ; KOIKE; Yoshiaki; (Annaka-shi, JP) ;
OISHI; Kazuhiro; (Annaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shin-Etsu Chemical Co., Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Shin-Etsu Chemical Co.,
Ltd.
Tokyo
JP
|
Family ID: |
63965148 |
Appl. No.: |
16/163999 |
Filed: |
October 18, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01B 3/28 20130101; C08G
77/26 20130101; C08G 77/20 20130101; C08L 2203/202 20130101; C08G
77/70 20130101; C08L 83/04 20130101; C08L 2205/025 20130101; C08G
77/12 20130101; C08K 5/14 20130101; H01B 3/46 20130101; C08K 5/14
20130101; C08L 83/04 20130101; C08L 83/00 20130101; C08L 83/00
20130101; C08L 83/00 20130101; C08K 5/56 20130101; C08L 83/00
20130101; C08L 83/04 20130101; C08L 83/14 20130101; C08L 83/04
20130101; C08L 83/04 20130101; C08G 77/80 20130101; C08L 83/04
20130101; C08K 5/544 20130101; C08K 5/3472 20130101 |
International
Class: |
C08L 83/14 20060101
C08L083/14; H01B 3/46 20060101 H01B003/46 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2017 |
JP |
2017-203038 |
Claims
1. A silicone composition comprising components (A) to (F), (A) 100
parts by mass of a raw rubber-like, at 25 degrees C.,
organopolysiloxane having at least two alkenyl groups each bonded
to a silicon atom, (B) 5 to 100 parts by mass of silica powder
having a specific surface area of 50 m.sup.2/g or more, (C)
platinum or a platinum compound in an amount of 1 to 1,000 ppm by
mass as a platinum atom, relative to the mass of component (A), (D)
0.01 to 5 parts by mass of a compound selected from an organic
silicon compound having a nitrogen-containing organic group and an
unsaturated hydrocarbon group, and benzotriazole and a derivative
thereof, (E) an addition reaction curing agent other than said
component (C), or an organic peroxide in an effective amount to
cure the composition, and (F) 0.01 to 5 parts by mass of an
aromatic hydrocarbon group-containing organopolysiloxane
represented by the following general formula (1):
(R.sup.1.sub.3SiO.sub.1/2).sub.n1(R.sup.1R.sup.2SiO.sub.2/2).sub.n2(R.sup-
.3SiO.sub.3/2).sub.n3(SiO.sub.4/2).sub.n4 (1), wherein R.sup.1 is,
independently of each other, a monovalent saturated aliphatic
hydrocarbon group having 1 to 10 carbon atoms, R.sup.2 is,
independently of each other, a monovalent aromatic hydrocarbon
group having 6 to 12 carbon atoms, R.sup.3 is, independently of
each other, a monovalent saturated aliphatic hydrocarbon group
having 1 to 10 carbon atoms or a monovalent aromatic hydrocarbon
group having 6 to 12 carbon atoms, wherein a proportion of the
number of the monovalent aromatic hydrocarbon group to the total
number of the substituents R.sup.1, R.sup.2 and R.sup.3 is 41% or
more and less than 46%, n1 is an integer of from 2 to 5, n2 is an
integer of from 15 to 25, a total of n3 and n4 is an integer of
from 0 to 3, 0<={n4/(n3+n4)}.times.100<=5, and a total of n1,
n2, n3 and n4 is an integer of from 17 to 30.
2. The silicone composition according to claim 1, wherein component
(A) comprises the following components (A-1) and (A-2); (A-1) a raw
rubber-like, at 25 degrees C., organopolysiloxane having 0.001 to
2% of the alkenyl group, based on the total number of the
substituents bonded to silicon atoms in an amount of 60 to 99 parts
by mass, and (A-2) a raw rubber-like, at 25 degrees C.,
organopolysiloxane having more than 2% and 20% or less of the
alkenyl group, based on the total number of substituents bonded to
silicon atoms, in an amount such that a total amount of components
(A-1) and (A-2) is 100 parts by mass.
3. The silicone composition according to claim 1 or 2, wherein
component (F) is represented by the following formula (2),
##STR00020## wherein R.sup.1 and R.sup.2 are as defined above, m is
an integer of from 0 to 3, m' is an integer of from 0 to 3, n' is
an integer of from 0 to 3, n is an integer of from 10 to 20, and a
total of m, m', n and n' is an integer of from 14 to 27.
4. The silicone composition according to claim 1 for a power
cable.
5. A cured silicone rubber product obtained by curing the silicone
composition according to claim 1.
6. The cured silicone rubber product according to claim 5, having a
tensile strength of 8 MPa or more, as determined according to the
Japanese Industrial Standards (JIS) K 6249: 2003.
7. The cured silicone rubber product according to claim 5 or 6,
having tear strength (crescent) of 25 N/mm or more, as determined
according to the Japanese Industrial Standards (JIS) K 6249:
2003.
8. The cured silicone rubber product according to claim 5, having
elongation at break of 600% or more, as determined according to the
Japanese Industrial Standards (JIS) K 6249: 2003.
9. A power cable provided with the cured silicone rubber product
according to claim 5.
Description
CROSS REFERENCE
[0001] This application claims the benefits of Japanese Patent
Application No. 2017-203038 filed on Oct. 20, 2017, the contents of
which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a silicone composition
which provides an electrically insulating silicone rubber,
specifically a silicone composition which may be used in connection
portions of power cables, such as intermediate connection portions
in which power cables are connected to each other, or terminal
connection portions in which power cable is connected to terminal
fittings. Further, the present invention relates to a power cable
provided with a cured product of the silicone composition at the
connecting portion.
[0003] An insulating member, particularly an electrically
insulating enclosure, is used in a connection portion of power
cables, such as an intermediate connection portion in which power
cables are connected to each other, or a terminal connection
portion in which power cable is connected to a terminal fitting.
The insulating member is formed from a silicone rubber having an
excellent electrical-insulation property, or an elastic rubber such
as an ethylene-propylene rubber (for short, EP rubber).
[0004] The following three methods are generally known for
connecting power cables. First, an insulating enclosure is slid
over a sheath of a power cable up to a connecting portion of the
power cable. Second, connection is formed while returning the
inversion of an inverted enclosure. The third is a cold shrinkage
method in which a core is inserted inside an insulating enclosure
beforehand, the enclosure is moved up to a connecting portion of an
electric power cable while being expanded by the core material and,
then, the core is pulled out, so that the enclosure shrinks. Third,
cold shrinkage method is preferable and used in the view of its
workability.
[0005] A rubber material to be used particularly for the
cold-shrinkage enclosure needs to be easily expanded in diameter,
to have a small tensile permanent strain which is a measure for
good restoration after the core is removed, a good tensile strength
and tear strength and, further, a good tracking resistance in
electric insulation. Preferable rubber physical properties are a
tensile strength of 8 MPa or more, a tear strength (crescent) of 25
N/mm or more, an elongation at break of 600% or more, and a target
tensile permanent strain of 20 or less under the 100% elongation
test condition, 22 hours at 180 degrees C., as determined in
accordance with JIS K 6249:2003.
[0006] Compared the silicone rubber with the EP rubber, the
silicone rubber has a smaller tensile permanent strain, so that it
has good restorability and excellent sealing and close fitting
properties between the silicone rubber and the cable after removing
the core. In addition, the silicone rubber may be of high
elongation, so that the diameter expansion is easy.
[0007] However, when the silicone rubber is used outdoors, it has a
problem that tracking occurs under leakage current to deteriorate.
In more severe environmental conditions, erosion is liable to occur
on the insulating member surface to shorten a life of the
enclosure. In order to improve the tracking resistance and to have
an excellent electrical insulation property in the a silicone
rubber, it is necessary to comprise a large content of aluminum
hydroxide and, as a result, the mechanical strength of the rubber
is worsen and the aforesaid physical properties of the rubber are
not satisfied.
[0008] Japanese Patent Application Laid-Open No. Sho-61-228062/1986
describes a flame-retardant silicone rubber composition comprising
an organosilicon compound having a nitrogen-containing organic
group and an unsaturated group, and a platinum-based compound.
Although the silicone rubber composition has an excellent flame
retardance, properties such as mechanical strength are insufficient
for connecting a power cable.
[0009] Japanese Patent Application Laid-Open No. Hei-9-284977/1997
describes an enclosure for connecting a power cable, which
comprises benzotriazole and a platinum compound. However, aluminum
hydroxide is essential and the mechanical strength is inferior.
[0010] Japanese Patent Application Laid-Open No. 2004-018701
describes a silicone rubber composition which comprises a phenyl
silicone and has tracking resistance. The silicone rubber
composition has mechanical strength, the tracking resistance is
improved to pass the standard of tracking resistance (IEC
Publication 587). Japanese Patent Application Laid-Open No.
2012-092305 describes a liquid silicone rubber composition for high
voltage electrical insulation parts, which contains silica
surface-treated with a vinyl group-containing organosilicon
compound.
PRIOR LITERATURES
[0011] Patent Literature 1: Japanese Patent Application Laid-Open
No. Sho-61-228062/1986 [0012] Patent Literature 2: Japanese Patent
Application Laid-Open No. Hei-9-284977/1997 [0013] Patent
Literature 3: Japanese Patent Application Laid-Open No.
2004-018701. [0014] Patent Literature 4: Japanese Patent
Application Laid-Open No. 2012-092305
SUMMARY OF THE INVENTION
[0015] However, the silicone rubber composition described in Patent
Literature 3 shows a somewhat large corrosion depth after erosion.
The silicone rubber composition described in Patent Literature 4
has a similar problem.
[0016] One of the purposes of the present invention is to provide a
silicone composition providing a cured product which has small
tensile permanent strain and excellent mechanical strength such as
tensile strength and tear strength, further has excellent
high-voltage electrical insulation and shows prevented progress of
destruction after erosion occurs. Further, the other purposes of
the present invention are to provide a power cable provided with
the cured product of the silicone composition as a connecting
member.
[0017] The present inventors have made research and found that a
cured product having an excellent tracking resistance even without
aluminum hydroxide and showing prevented progress of destruction
after erosion occurs is provided from a silicone composition which
comprises a raw rubber-like organopolysiloxane having at least two
alkenyl groups each bonded to a silicon atom, (B) silica powder,
(C) platinum or a platinum compound, (D) a compound selected from
an organic silicon compound having a nitrogen-containing organic
group and an unsaturated hydrocarbon group, and benzotriazole or a
derivative thereof, and (E) a curing agent and further comprises a
specific amount of (F) an organopolysiloxane having an aromatic
hydrocarbon group in a specific amount, particularly a silicone
oil.
[0018] Thus, the present invention provides a silicone composition
comprising components (A) to (F),
[0019] (A) 100 parts by mass of a raw rubber-like, at 25 degrees
C., organopolysiloxane having at least two alkenyl groups each
bonded to a silicon atom,
[0020] (B) 5 to 100 parts by mass of silica powder having a
specific surface area of 50 m.sup.2/g or more,
[0021] (C) platinum or a platinum compound in an amount of 1 to
1,000 ppm by mass as a platinum atom, relative to the mass of
component (A),
[0022] (D) 0.01 to 5 parts by mass of a compound selected from an
organic silicon compound having a nitrogen-containing organic group
and an unsaturated hydrocarbon group, and benzotriazole and a
derivative thereof,
[0023] (E) an addition reaction curing agent other than said
component (C), or an organic peroxide in an effective amount to
cure the composition, and
[0024] (F) 0.01 to 5 parts by mass of an aromatic hydrocarbon
group-containing organopolysiloxane represented by the following
general formula (1):
(R.sup.1.sub.3SiO.sub.1/2).sub.n1(R.sup.1R.sup.2SiO.sub.2/2).sub.n2(R.su-
p.3SiO.sub.3/2).sub.n3(SiO.sub.4/2).sub.n4 (1),
wherein R.sup.1 is, independently of each other, a monovalent
saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms,
R.sup.2 is, independently of each other, a monovalent aromatic
hydrocarbon group having 6 to 12 carbon atoms, R.sup.3 is,
independently of each other, a monovalent saturated aliphatic
hydrocarbon group having 1 to 10 carbon atoms or a monovalent
aromatic hydrocarbon group having 6 to 12 carbon atoms, wherein a
proportion of the number of the monovalent aromatic hydrocarbon
group to the total number of the substituents R.sup.1, R.sup.2 and
R.sup.3 is 41% or more and less than 46%, n1 is an integer of from
2 to 5, n2 is an integer of from 15 to 25, a total of n3 and n4 is
an integer of from 0 to 3, 0<={n4/(n3+n4)}.times.100<=5, and
a total of n1, n2, n3 and n4 is an integer of from 17 to 30.
[0025] The present invention provides the silicone composition,
wherein component (A) preferably comprises the following components
(A-1) and (A-2);
[0026] (A-1) a raw rubber-like, at 25 degrees C.,
organopolysiloxane having 0.001 to 2% of the alkenyl group, based
on the total number of the substituents bonded to silicon atoms in
an amount of 60 to 99 parts by mass, and
[0027] (A-2) a raw rubber-like, at 25 degrees C.,
organopolysiloxane having more than 2% and 20% or less of the
alkenyl group, based on the total number of substituents bonded to
silicon atoms, in an amount such that a total amount of components
(A-1) and (A-2) is 100 parts by mass.
[0028] The present invention further provides a silicone
composition for a power cable, a cured silicone rubber product
obtained from the silicone composition, and a power cable provided
with the cured silicone rubber product.
[0029] The silicone rubber product obtained by curing the present
silicone composition has small tensile permanent strain, excellent
mechanical strength such as tensile strength and tear strength, and
excellent high-voltage electrical insulation and prevented progress
of destruction after erosion occurs. Accordingly, the present
silicone composition is suitable for connecting a power cable,
where a power cable is provided with the cured product of the
silicone composition as a connecting member.
[0030] The present invention will be described below in detail. The
average polymerization degree described in the present invention is
a weight average molecular weight determined by gel permeation
chromatography, i.e., GPC, and reduced to polystyrene. Conditions
in GPC were as follows.
[GPC Conditions]
Solvent: Tetrahydrofuran
[0031] Flow Rate: 0.6 mL/min. Detector: Differential refractive
index detector (RI)
Columns:
TSK Guardcolumn SuperH-L
[0032] TSKgel SuperH4000 (6.0 mmI.D..times.15 cm.times.1) TSKgel
SuperH3000 (6.0 mmI.D..times.15 cm.times.1) TSKgel SuperH2000 (6.0
mmI.D..times.15 cm.times.2)
[0033] all provided by TOSOH Cop.
Column Temperature: 40 degrees C. Injection Volume: 20 .mu.L of a
0.5% by weight solution in THF.
(A) Alkenyl Group-Containing Raw Rubber-Like Organopolysiloxane
[0034] Component (A) is a raw rubber-like, at 25 degrees C.,
organopolysiloxane having at least two alkenyl groups each bonded
to a silicon atom. Examples of the alkenyl group include a vinyl
group, an allyl group, a butenyl group, and a hexenyl group,
preferably a vinyl group. The alkenyl groups may be present at the
ends of the molecular chain, at the side chains, or both. In the
present invention, the term "raw rubber-like" means a very viscous
state showing a viscosity of 10,000 mPas or more, particularly
100,000 mPas or more, or a non-liquid state, such as pasty or
solid, having no self-fluidity both at room temperature, i.e. 25
degrees C. In the present invention, the viscosity is determined by
a rotational viscometer.
[0035] The component (A) are preferably the following components
(A-1) and (A-2).
[0036] (A-1) a raw rubber-like, at 25 degrees C.,
organopolysiloxane having 0.001 to 2% of the alkenyl group, based
on the total number of the substituents bonded to silicon
atoms.
[0037] (A-2) a raw rubber-like, at 25 degrees C.,
organopolysiloxane having more than 2% and 20% or less of the
alkenyl group, based on the total number of substituents bonded to
silicon atoms.
[0038] On account of the combination of components (A-1) and (A-2),
the cured product obtained by curing the silicone composition has
an excellent rubber properties such as tear strength. Thus, the
present silicone composition preferably comprises the combination
of (A-1) the organopolysiloxane having a relatively small amount of
an alkenyl group and (A-2) the organopolysiloxane having a
relatively large amount of an alkenyl group at a specific ratio.
The amount of component (A-1) is 60 to 99 parts by mass, preferably
90 to 99 parts by mass, relative to a total 100 parts by mass of
components (A-1) and (A-2).
[0039] The components (A-1) and (A-2) are preferably ones
represented by the following average composition formula (2):
R.sub.aSiO.sub.(4-a)/2 (2)
wherein R is, independently of each other, unsubstituted or
substituted, monovalent hydrocarbon group having 1 to 12 carbon
atoms, a is a positive number of 1.95 to 2.04, and at least one of
R is an alkenyl group.
[0040] The aforesaid organopolysiloxane is generally prepared by a
cohydrolysis condensation of one or more organohalogenosilanes or a
ring opening polymerization of a cyclic polysiloxane, such as a
trimer or tetramer of a siloxane, in the presence of an alkaline or
acidic catalyst. The present organopolysiloxane is mainly a linear
diorganopolysiloxane, but may have a branch. The organopolysiloxane
may be a combination of two or more kinds of the
organopolysiloxanes having different molecular structures.
[0041] Components (A-1) and (A-2) will be described below in
detail.
[0042] Component (A-1) has an alkenyl group in an amount of 0.001
to 2%, preferably 0.001 to 1%, based on the total number of the
substituents each bonded to a silicon atom, that is, the total
number of R in the aforesaid formula (2). The alkenyl group is as
defined above, preferably a vinyl group. The alkenyl group may be
present at the end of the molecular chain, at the side chain, or
both.
[0043] For R in the formula (2), the group other than the alkenyl
group is an unsubstituted or substituted, monovalent hydrocarbon
group having 1 to 12, preferably 1 to 8 carbon atoms; such as an
alkyl group such as a methyl group, an ethyl group, a propyl group,
a butyl group, a hexyl group and a dodecyl group; a cycloalkyl
group such as a cyclohexyl group; an aryl group such as a phenyl
group and a tolyl group; an aralkyl group such as a .beta.-phenyl
group; and those hydrocarbon groups wherein a part or all of the
hydrogen atoms bonded to a carbon atom of these groups is
substituted with a substituent such as a halogen atom and a cyano
group; such as a chloromethyl group, a trifluoropropyropyl group,
or a cyanoethyl group. Particularly, it is preferable that 80% or
more, more preferably 90% or more, of the total number of R other
than the alkenyl group is a methyl group.
[0044] "a" is a positive number of 1.95 to 2.04, preferably 1.97 to
2.02. Preferred is that the terminals of the molecular chain 26 are
blocked with triorganosilyl groups, such as a trimethylsilyl group,
a dimethylvinylsilyl group and a trivinylsilyl group, particularly
blocked with an alkenyl group-containing silyl group.
[0045] An average polymerization degree of the component (A-1) is
preferably 3,000 or more, and preferably at most 100,000. In
particular, component (A-1) has the average polymerization degree
of 5,000 to 20,000. The average polymerization degree is a weight
average molecular weight as determined by gel permeation
chromatography (GPC), reduced to polystyrene as a standard
substance. The determination conditions are as described above.
[0046] Component (A-2) has an alkenyl group in an amount of more
than 2% to 20%, preferably 3 to 15%, based on the total number of
the substituents each bonded to a silicon atom, that is, the total
number of R in the aforesaid formula (2). The alkenyl group is as
defined above, preferably a vinyl group. The alkenyl group may be
present at the end of the molecular chain, at the side chain, or
both.
[0047] For R in the formula (2), the group other than the alkenyl
group is an unsubstituted or substituted, monovalent hydrocarbon
group having 1 to 12, preferably 1 to 8 carbon atoms, as defined
for component (A-1) above. Particularly, it is preferable that 80%
or more, more preferably 90% or more, of the total number of R
other than the alkenyl group is a methyl group.
[0048] "a" is a positive number of 1.95 to 2.04, preferably 1.97 to
2.02. Preferred is that the terminals of the molecular chain are
blocked with triorganosilyl groups, such as a trimethylsilyl group,
a dimethylvinylsilyl group and a trivinylsilyl group, particularly
blocked with an alkenyl group-containing silyl group.
[0049] An average polymerization degree of the component (A-2) is
preferably 3,000 or more, and preferably at most 100,000. In
particular, component (A-2) has the average polymerization degree
of 5,000 to 20,000. The average polymerization degree is a weight
average molecular weight as determined by gel permeation
chromatography (GPC), reduced to polystyrene as a standard
substance. The determination conditions are as described above.
(B) Silica Powder
[0050] The silica powder has a specific surface area of 50
m.sup.2/g or more, preferably 100 to 400 m.sup.2/g, as determined
by a BET method, and is, particularly, silica fine powder. On
account of the silica powder, a cured silicone rubber product has
an excellent mechanical strength. Examples of the silica powder
include fumed silica called "dry silica" and precipitated silica
called "wet silica". Among these, fumed silica is preferable.
Preferably, the surface of these silica is hydrophobized with an
organosilicon compound such as an organopolysiloxane, an
organopolysilazane, a chlorosilane and an alkoxysilane. These
silica powder may be used single or in combination of two or more
of kinds of them.
[0051] The amount of the silica powder is 5 to 100 parts by mass,
preferably 10 to 90 parts by mass, particularly 30 to 80 parts by
mass, relative to 100 parts by mass of component (A). If the amount
is smaller than the lower limit, a sufficient reinforcing effect is
not obtained. If the amount is larger than the upper limit, the
processability of the composition deteriorates and the physical
properties of the resulting cured silicone rubber product
deteriorate.
(C) Platinum or a Platinum Compound
[0052] The present silicone composition comprises platinum or a
platinum compound. The platinum or the platinum compound improves
flame retardancy and tracking resistance of the cured silicone
rubber. By the use of component (C) in combination with components
(D) and (F) described later, higher tracking resistance is
obtained.
[0053] Examples of component (C) is an elementary platinum,
particulate platinum adsorbed on a carrier such as silica, alumina
or silica gel, a platinum compound such as a platinum complex,
platinum chloride, chloroplatinic acid, a complex of chloroplatinic
acid hexahydrate with olefin or a divinyl dimethyl polysiloxane, an
alcohol solution of chloroplatinic acid hexahydrate, furthermore,
an aldehyde compound of chloroplatinic acid hexahydrate, and a
platinum complex with various olefins or an ether compound. The
amount of component (C) may be 1 to 1,000 ppm by mass, preferably 5
to 500 ppm by mass, as a platinum group metal, relative to the mass
of component (A).
(D) Organic Silicon Compound Having a Nitrogen-Containing Organic
Group and an Unsaturated Hydrocarbon Group and/or Benzotriazole or
a Derivative Thereof
[0054] The present silicone composition comprises an organic
silicon compound having a nitrogen-containing organic group and an
unsaturated hydrocarbon group and/or benzotriazole or a derivative
thereof. By the use of component (D) in combination with the
components (C) and (F), tracking resistance is further improved. As
long as the component (D) is incorporated within the range of the
amount described later, it does not affect the physical properties
after curing, so that a cured product has an excellent mechanical
strength. Component (D) may be at least one of the organic silicon
compound having a nitrogen-containing organic group and an
unsaturated hydrocarbon group, and benzotriazole or a derivative
thereof. Preferred is a combination of the organic silicon compound
having a nitrogen-containing organic group and an unsaturated
hydrocarbon group, with benzotriazole or a derivative thereof.
[0055] The nitrogen-containing organic group of the organic silicon
compound is, for instance, an aminoalkyl group having 1 to 5 carbon
atoms, preferably 1 to 3 carbon atoms, and imino group. The
unsaturated hydrocarbon group is, for instance, an alkenyl group
having 2 to 5 carbon atoms, preferably a vinyl group. The organic
silicon compound is an organosilane or an organosiloxane. The
nitrogen-containing organic group and the unsaturated hydrocarbon
group may be bonded to the same silicone atom or to different
silicon atoms, or may form a group having both the unsaturated
hydrocarbon group and the nitrogen-containing organic group to bond
to a silicon atom. Examples of the groups other than the
nitrogen-containing organic group and the unsaturated hydrocarbon
group include an alkyl group having 1 to 10 carbon atoms, and an
alkoxy group having 1 to 5 carbon atoms.
[0056] The group having the unsaturated hydrocarbon group and the
nitrogen-containing organic group includes, for instance, the
following groups.
##STR00001##
wherein n is an integer of from 1 to 3.
[0057] Examples of such organic silicon compounds include the
organosilanes represented by the following formulas, or siloxanes
obtained by hydrolyzing these.
##STR00002##
[0058] The organic silicon compound may be a cohydrolyzable
siloxane of a silane having the nitrogen-containing organic group
such as an aminoalkyl group, preferably having 1 to 3 carbon atoms,
and an imino group with a silane having the unsaturated hydrocarbon
group such as an alkenyl group, preferably a vinyl group or a
propenyl group. Alternatively, the organic silicon compound may be
a cohydrolyzed siloxane of a silane having the nitrogen-containing
organic group and a silane having the unsaturated hydrocarbon group
with a silane having none of these groups. For instance, these
siloxanes may be the following ones.
##STR00003##
wherein m is an integer of 1 or more, preferably an integer of from
1 to 30, n is an integer of 1 or more, preferably an integer of
from 1 to 50, p is an integer of 1 or more, preferably an integer
of from 1 to 500, q is an integer of 2 or more, preferably an
integer of from 3 to 10.
[0059] Examples of benzotriazole or derivatives thereof is
benzotriazole, 1-methylbenzotriazole, 5,6-dimethylbenzothiazole,
2-phenylbenzothiazole, 1-hydroxybenzotriazole, methyl
1-benzotriazole carboxylate, and the benzotriazole derivatives
represented by the following formulas.
##STR00004##
wherein n is an integer of from 0 to 6.
##STR00005##
wherein m is an integer of from 1 to 6.
##STR00006##
wherein "l" is an integer of from 1 to 6, and R.sup.6 is an alkyl
group or a trialkylsilyl group.
[0060] When the benzotriazole is solid at room temperature, it may
be made into a solution in alcohol or into a paste such as a
silicone oil paste or a silicone raw rubber paste, in order to
improve dispersibility in the composition.
[0061] The amount of component (D) is 0.01 to 5 parts by mass,
preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of
component (A). When both of the organic silicon compound and the
benzotriazoles are incorporated, the aforesaid amount is a total
amount of the both. If the amount is smaller than the lower limit,
tracking resistance is not improved. Even if the amount is larger
than the upper limit, the tracking resistance-improving effect is
not increased any more, and curing inhibition may occur in an
addition curing reaction, which is not preferable.
(E) Curing Agent
[0062] The present silicone composition further comprises a curing
agent. The curing agent may be an addition reaction curing agent or
an organic peroxide which are conventionally known as a curing
agent for an alkenyl group-containing silicone composition.
Examples of the curing agents for addition reactions include an
organohydrogenpolysiloxane and platinum-based catalysts other than
the aforesaid component (C). The amount of the curing agent may be
as required, i.e. an effective amount, to cure the present silicone
composition and may be appropriately adjusted as in conventional
compositions.
[0063] The organohydrogerpolysiloxane is, for instance, represented
by the following formula (3):
H.sub.bR.sup.3.sub.cSiO.sub.(4-b-c)/2 (3)
wherein R.sup.3 is, independently of each other, a substituted or
unsubstituted, monovalent hydrocarbon group, 0<b<=3,
0<=c<3, and 0<b+c<=3. The organohydrogenpolysiloxane
may be linear, branched, or cyclic as long as it has two or more
hydrosilyl groups, i.e. SiH group, in the molecule. The
organohydrogenpolysiloxane preferably has an average degree of
polymerization of 300 or less.
[0064] Examples of the organohydrogenpolysiloxane include a
diorganopolysiloxane end-capped with dimethylhydrogensilyl groups,
a copolymer of dimethylsiloxane units, methylhydrogensiloxane units
and terminal trimethylsiloxy units, a low viscosity fluid
comprising dimethylhydrogensiloxane units
(H(CH.sub.3).sub.2SiO.sub.0.5 units) and SiO.sub.2 units,
1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane,
1-propyl-3,5,7-trihydrogen-1,3,5,7-tetramethyl cyclotetrasiloxane,
and
1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane.
[0065] The amount of the organohydrogenpolysiloxane is preferably
such that a ratio of the number of hydrogen atoms bonded to the
silicon atoms, i.e. SiH group, in the organohydrogenpolysiloxane to
the total number of the alkenyl groups in (A) the
organopolysiloxane, i.e. H/Vi, is preferably 0.5 to 10, more
preferably 1 to 5.
[0066] Examples of the platinum-based catalyst include an
elementary platinum, platinum compounds such as a platinum complex,
a chloroplatinic acid, a complex of a chloroplatinic acid with
alcohol, aldehyde, ether and various olefins. The platinum-based
catalyst other than component (C) may not be used because component
(C) functions as the platinum-based catalyst for the addition
reaction. Alternatively, the platinum-based catalyst may be used in
combination with component (C), wherein the total amount of
component (C) and the platinum-based catalyst other than component
(C) may be 2 to 2,000 ppm by mass, preferably 6 to 1,000 ppm by
mass, as platinum metal, relative to the mass of component (A).
[0067] Examples of the organic peroxide include benzoyl peroxide,
2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide,
o-methylbenzoyl peroxide, 2,4-dicumyl peroxide,
2,5-dimethyl-bis(2,5-t-butylperoxy)hexane, di-t-butyl peroxide, and
t-butyl perbenzoate. The amount of the organic peroxide is 0.1 to 5
parts by mass, relative to 100 parts by mass of component (A).
(F) Aromatic Hydrocarbon Group-Containing Organopolysiloxane
[0068] The present silicone composition is characterized in that
this comprises the aromatic hydrocarbon group-containing
organopolysiloxane represented by the following general formula
(1). The aromatic hydrocarbon group-containing organopolysiloxane
further improves tracking resistance.
(R.sup.1.sub.3SiO.sub.1/2).sub.n1(R.sup.1R.sup.2SiO.sub.2/2).sub.n2(R.su-
p.3SiO.sub.3/2).sub.n3(SiO.sub.4/2).sub.n4 (1),
wherein R.sup.1 is, independently of each other, a monovalent
saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms,
R.sup.2 is, independently of each other, a monovalent aromatic
hydrocarbon group having 6 to 12 carbon atoms, R.sup.3 is,
independently of each other, a monovalent saturated aliphatic
hydrocarbon group having 1 to 10 carbon atoms or a monovalent
aromatic hydrocarbon group having 6 to 12 carbon atoms, wherein a
percentage of the number of a monovalent aromatic hydrocarbon
group, based on the total number of the substituents R.sup.1,
R.sup.2 and R.sup.3, is 41% or more and less than 46%, preferably
41 to 43%, n1 is an integer of from 2 to 5, n2 is an integer of
from 15 to 25, the total of n3 and n4 is an integer of from 0 to 3,
0<={n4/(n3+n4)}.times.1.00<=5, and the total of n1, n2, n3
and n4 is an integer of from 17 to 30.
[0069] In the above formula (1), n1 is an integer of from 2 to 5,
preferably 2 or 3, n2 is an integer of from 15 to 25, preferably
1.5 to 22, the total of n3 and n4 is an integer of from 0 to 3,
preferably 0 or 1, 0<={n4/(n3+n4)}.times.100<=5, preferably
0<={n4/(n3+n4)}.times.100<=1, and the total of n1, n2, n3 and
n4 is an integer of from 17 to 30, preferably an integer of from 17
to 28. The organopolysiloxane is particularly in the form of an
oil.
[0070] If any of n1, n2, n3 and n4 exceeds the aforesaid range, no
protective effect for a material surface is obtained, so that the
effect of preventing the progress of erosion cannot be attained. If
the siloxane chain length, i.e. the total of n1+n2+n3+n4, is less
than the aforesaid lower limit, the effect of preventing the
progress of erosion cannot be attained.
[0071] A branched structure (T unit and/or Q unit) may be
introduced into the linear organopolysiloxane so that n1, n2, n3
and n4 satisfy the aforesaid range in the present aromatic
hydrocarbon group-containing organopolysiloxane. Then, the polarity
between the organopolysiloxane and the other components may also be
adjusted and the tracking resistance can be thereby controlled. The
present organopolysiloxane has a siloxane chain length, that is,
total of n1+n2+n3+n4, of 17 to 30, preferably 17 to 28, and the
amount of the aromatic hydrocarbon group is 41% or more and less
than 46%, preferably 41 to 43 mole %, based on the total number of
the substituents each bonded to the silicon atom, that is, R.sup.1,
R.sup.2 and R.sup.3. On account of the siloxane chain length,
erosion can be suppressed. In particular, when the amount of the
aromatic hydrocarbon group is less than the aforesaid lower limit
or exceeds the aforesaid upper limit, the obtained cured product
shows a large erosion depth after erosion occurs and the progress
of destruction to form a through hole cannot be prevented.
[0072] In the aforesaid formula (1), examples of R.sup.1 include an
alkyl group such as a methyl group, an ethyl group, a propyl group,
a butyl group, a hexyl group, and a cyclohexyl group. Among these,
a methyl group is preferred. Examples of R.sup.2 is an aryl group
such as a phenyl group and a tolyl group, and an aralkyl group such
as a benzyl group and a 2-phenylethyl group. Among these, a phenyl
group is preferred. R.sup.3 is selected from the groups defined for
R.sup.1 and R.sup.2.
[0073] Component (F) is preferably an organopolysiloxane
represented by the following formula (2):
##STR00007##
wherein R.sup.1 and R.sup.2 are as defined above, the amount of the
monovalent aromatic hydrocarbon group is 41% or more and less than
46%, based on the total number of the substituents each bonded to
the silicon atom, that is, R.sup.1 and R.sup.2, m is an integer of
from 0 to 3, m' is an integer of from 0 to 3, n' is an integer of
from 0 to 3, n is an integer of from 10 to 20, and the total of m,
m', n and n' is an integer of from 14 to 27.
[0074] In the formula (2), m is an integer of from 0 to 3,
preferably 0 to 2, m' and n' are integers of from 0 to 3,
preferably 0 or 1, and n is an integer of from 10 to 20, preferably
12 to 18, m+m'+n+n' is an integer of from 14 to 27, preferably 17
to 25.
[0075] The amount of component (F) is 0.01 to 5 parts by mass,
preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of
component (A). If the amount of the component (F) is less than the
aforesaid lower limit, a sufficient effect is not attained. If the
amount of the component (F) exceeds the aforesaid upper limit,
component (F) may bleed on the rubber surface to cause stain on the
surface of the cured rubber product.
Other Additives
[0076] The silicone composition of the present invention may
comprise, if necessary, other additives which are conventionally
added in a silicone composition, in addition to the aforesaid
components. The amount of the additives may be appropriately
determined as in conventional silicone compositions as long as the
effects of the present invention are not disturbed.
[0077] Examples of the additives include a diorganopolysiloxane as
a dispersant, such as dimethylpolysiloxane having hydroxyl groups
at the terminals and methylvinylpolysiloxane; a low-molecular
weight organosilicon compound such as diphenylsilanediol,
hexamethyldisilazane and organoalkoxysilane; a wetter such as
water; inorganic fillers such as diatomaceous earth, quartz powder,
calcium carbonate, aluminum hydroxide and carbon black; a
heat-resistant agent such as cerium hydroxide, cerium silanolate
and cerium fatty acid salt; a fatty acid and a metallic salt
thereof, such as stearic acid, zinc stearate and calcium stearate;
mold releasing agents such as wax; metal oxide such as iron oxide
and titanium oxide; and pigments.
[0078] The present silicone composition may be prepared by
uniformly mixing the aforesaid components using a rubber kneading
machine, such as a two-roll mill, a banbury mixer, and a dough
mixer (kneader). The mixing order, the temperature condition, and
the time are not particularly limited and may be as in conventional
methods.
[0079] A cured silicone rubber product is obtained by vulcanizing
the present silicone composition under heating. The molding and
curing method of the composition may be appropriately selected. For
instance, the composition is molded by a method such as pressure
molding, transfer molding, extrusion molding, injection molding and
calender molding. The curing method may be selected depending on
the kind of a curing agent. The cured silicone rubber product
obtained from the present silicone composition has an excellent
tracking resistance. Further, the obtained cured product has a
tensile strength of 8 MPa or more, a tear strength (crescent) of 25
N/mm or more, and an elongation at break of 600% or more, as
determined in accordance with the Japanese Industrial.
Standards(JIS) K 6249:2003.
EXAMPLES
[0080] The present invention will be explained below in further
detail with reference to a series of the Examples and the
Comparative Examples, though the present invention is in no way
limited by these Examples.
[Method for Determination of Properties of Cured Products]
[Mechanical Properties: Hardness, Tensile Strength, Tear Strength
(Crescent Shape), Elongation at Break, and Tensile Permanent
Strain]
[0081] Each silicone composition was compression-molded under
heating conditions of 165 degrees C. for 10 minutes into a sheet
shape having a thickness of 2 mm. Further, the sheet was subjected
to secondary vulcanization at 200 degrees C. for 4 hours to obtain
a silicone rubber sheet. Mechanical properties of the sheet were
determined according to the Japanese Industrial Standards (JIS) K
6249:2003. The results are as shown in Table 1.
[Tracking Test]
[0082] A tracking test was carried out according to the IEC
Publ.587 Standards, Method. 1 test, to thereby evaluate a silicone
rubber sheet whether pass or fail.
[0083] Thus, the silicone rubber sheet having a thickness of 6 mm
was prepared similarly as in the preceding paragraph 0061. A
contaminated liquid (aqueous solution of 0.1 mass % of NH.sub.4Cl
and 0.02 mass % of a nonionic surfactant) was dropped from an upper
electrode on the five test sheets at a rate of 0.6 ml/min for 6
hours, at an applied voltage of 3.5 kV or 4.5 kV, a frequency of 50
Hz and an inter-electrode distance of 50 mm. When a track occurred
on the test sheet and the sheet was broken by the leakage current,
the test sheet was evaluated as fail. When the sheet was not
broken, the test sheet was evaluated as pass. The presence or
absence of the through holes on the five test sheets was confirmed,
and the number of the test sheets having the through hole is shown
in Table 1. Further, the minimum destruction time in minute, the
maximum erosion depth in mm, and the average weight loss in %, are
as shown in Table 1.
Preparation Example 1
[0084] 95 parts by mass of (A-1) a raw rubber-like
organopolysiloxane comprising 99.975 mol % of dimethylsiloxane
units and 0.025 mol % of dimethylvinylsiloxane units and having an
average polymerization degree of about 8,000, 5 parts by mass of
(A-2) a raw rubber-like organopolysiloxane comprising 89.993 mol %
of dimethylsiloxane units and 9.982 mol % of methylvinylsiloxane
units and having an average polymerization degree of about 8,000,
35 parts by mass of (B) fumed silica hydrophobilized by
dichlorodimethylsilane and having a specific surface area of 300
m.sup.2/g, and 3 parts by mass of dimethylpolysiloxane as a
dispersant which had silanol groups at the both terminals, an
average polymerization degree of 13, and a viscosity at 25 degrees
C. of 15 mm.sup.2/s were kneaded with a kneader. Further, 1.0 part
by mass of (D) polymer A represented by the following formula (3)
was added to the mixture, kneaded, and heated at 180 degrees C. for
3 hours to obtain mixture A.
##STR00008##
Preparation Example 2
[0085] 99 parts by mass of (A-1) a raw rubber-like
organopolysiloxane comprising 99.975 mol % of dimethylsiloxane
units and 0.025 mol % of dimethylvinylsiloxane units and having an
average polymerization degree of about 8,000, 1 part by mass of
(A-2) a raw rubber-like organopolysiloxane comprising 97.000 mol %
of dimethylsiloxane units, 2.975 mol % of methylvinylsiloxane units
and 0.025 mol % of dimethylvinylsiloxane units and having an
average polymerization degree of about 8,000, 35 parts by mass of
(B) fumed silica hydrophobilized by dichlorodimethylsilane and
having a specific surface area of 300 m.sup.2/g, and 3 parts by
mass of dimethylpolysiloxane as a dispersant which had silanol
groups at the both terminals, an average polymerization degree of
13, and a viscosity at 25 degrees C. of 15 mm.sup.2/s were kneaded
with a kneader. Further, 1.0 part by mass of (D) polymer A
represented by the aforesaid formula (3) was added to the mixture,
kneaded, and heated at 180 degrees C. for 3 hours to obtain mixture
B.
Preparation Example 3
[0086] 90 parts by mass of (A-1) a raw rubber-like
organopolysiloxane comprising 98.500 mol % of dimethylsiloxane
units, 1.475 mol % of methylvinylsiloxane units and 0.025 mol % of
dimethylvinylsiloxane units and having an average polymerization
degree of about 8,000, 10 parts by mass of (A-2) a raw rubber-like
organopolysiloxane comprising 90.000 mol % of dimethylsiloxane
units, 9.975 mol % of methylvinylsiloxane units and 0.025 mol % of
dimethylvinylsiloxane units and having an average polymerization
degree of about 8,000, 35 parts by mass of (B) fumed silica
hydrophobilized by dichlorodimethylsilane and having a specific
surface area of 300 m.sup.2/g, and 3 parts by mass of
dimethylpolysiloxane as a dispersant which had silanol groups at
the both terminals, an average polymerization degree of 13, and a
viscosity at 25 degrees C. of 15 mm.sup.2/s were kneaded with a
kneader. Further, 1.0 part by mass of (D) polymer A represented by
the aforesaid formula (3) was added to the mixture, kneaded, and
heated at 180 degrees C. for 3 hours to obtain mixture C.
Preparation Example 4
[0087] 95 parts by mass of (A-1) a raw rubber-like
organopolysiloxane comprising 99.975 mol % of dimethylsiloxane
units and 0.025 mol % of dimethylvinylsiloxane units and having an
average polymerization degree of about 8,000, 5 parts by mass of
(A-2) a raw rubber-like organopolysiloxane having 89.993 mol % of
dimethylsiloxane units, 9.982 mol % of methylvinylsiloxane units
and 0.025 mol % of dimethylvinylsiloxane units and having an
average polymerization degree of about 8,000, 35 parts by mass of
(B) fumed silica hydrophobilized by dichlorodimethylsilane and
having a specific surface area of 300 m.sup.2/g, and 3 parts by
mass of dimethylpolysiloxane as a dispersant which had silanol
groups at the both terminals, an average polymerization degree of
13, and a viscosity at 25 degrees C. of 15 mm.sup.2/s were kneaded
with a kneader, and heated at 180 degrees C. for 3 hours to obtain
mixture D.
Example 1
[0088] 100 parts by mass of mixture A obtained in Preparation
Example 1, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
parts by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, 0.15 part by mass of (D)
benzotriazole and 1 part by mass of (F) silicone oil which is
represented by the following formula and had 42% of a phenyl group,
based on the total number of the substituents were mixed by a
two-roll mill. Further, 0.6 part by mass of (E) dicumyl peroxide
was added as a curing agent and mixed by the two-roll mill to
prepare silicone composition 1. Silicone composition 1 was molded
and cured according to the aforesaid methods so as to prepare cured
rubber products. The properties of the products were evaluated. The
results are as shown in Table 1.
##STR00009##
wherein the amount of the phenyl group is 42 mole %.
Example 2
[0089] 100 parts by mass of mixture A obtained in Preparation
Example 1, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
part by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, 0.15 part by mass of (D)
benzotriazole and 1 part by mass of (F) silicone oil which is
represented by the following formula, comprising T units, and had
41% of a phenyl group, based on the total number of the
substituents were added and mixed by a two-roll mill. Further, 0.6
part by mass of (E) dicumyl peroxide was added as a curing agent
and mixed by the two-roll mill to prepare silicone composition 2.
Silicone composition 2 was molded and cured according to the
aforesaid methods so as to prepare cured rubber products. The
properties of the products were evaluated. The results are as shown
in Table 1.
##STR00010##
wherein the amount of the phenyl group is 41 mole %.
Example 3
[0090] 100 parts by mass of mixture A obtained in Preparation
Example 1, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
part by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, 0.15 part by mass of (D)
benzotriazole and 1 part by mass of (F) silicone oil which is
represented by the following formula and had 45% of a phenyl group,
based on the total number of the substituents were added and mixed
by a two-roll mill. Further, 0.6 part by mass of (E) dicumyl
peroxide was added as a curing agent and mixed by the two-roll mill
to prepare silicone composition 3. Silicone composition 3 was
molded and cured according to the aforesaid methods so as to
prepare cured rubber products. The properties of the products were
evaluated. The results are as shown in Table 1.
##STR00011##
wherein the amount of the phenyl group is 45 mole %.
Example 4
[0091] 100 parts by mass of mixture A, 0.1 part by mass of a
solution of chloroplatinic acid hexahydrate in 2-ethylhexanol,
containing 2 mass % of platinum, 0.1 part by mass of carbon black,
5.0 parts by mass of titanium oxide, 0.5 part by mass of cerium
oxide, 0.15 part by mass of (D) benzotriazole and 1 part by mass of
(F) silicone oil which is represented by the following formula,
comprising T units, and had 41% of a phenyl group, based on the
total number of the substituents were added and mixed by a two-roll
mill. Further, 0.91 part by mass of (E) methylhydrogenpolysiloxane
having SiH group at a side chain (a
dimethylsiloxane-methylhydrogensiloxane copolymer whose both
terminals are capped with a trimethylsiloxy group, having a
polymerization degree of 40 and a SiH group of 0.074 mol/g) was
added as a curing agent and mixed by the two-roll mill to prepare
silicone composition 4. Silicone composition 4 was molded and cured
according to the aforesaid methods so as to prepare cured rubber
products. The properties of the products were evaluated. The
results are as shown in Table 1.
##STR00012##
wherein the amount of the phenyl group is 41 mole %.
Example 5
[0092] 100 parts by mass of mixture B obtained in Preparation
Example 2, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
part by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, 0.15 part by mass of (D)
benzotriazole and 1 part by mass of (F) silicone oil which is
represented by the following formula and had 42% of a phenyl group,
based on the total number of the substituents were added and mixed
by a two-roll mill. Further, 0.6 part by mass of (E) dicumyl
peroxide was added as a curing agent and mixed by the two-roll mill
to prepare silicone composition 5. Silicone composition 5 was
molded and cured according to the aforesaid methods so as to
prepare cured rubber products. The properties of the cured products
were evaluated. The results are as shown in Table 1.
##STR00013##
wherein the amount of the phenyl group is 42 mole %.
Example 63
[0093] 100 parts by mass of mixture C obtained in Preparation
Example 3, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
part by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, 0.15 part by mass of (D)
benzotriazole and 1 part by mass of (F) silicone oil which is
represented by the following formula and had 42% of a phenyl group,
based on the total number of the substituents were added and mixed
by a two-roll mill. Further, 0.6 part by mass of (E) dicumyl
peroxide was added as a curing agent and mixed by the two-roll mill
to prepare silicone composition 6. Silicone composition 6 was
molded and cured according to the aforesaid method so as to prepare
cured rubber products. The properties of the cured products were
evaluated. The results are as shown in Table 1.
##STR00014##
wherein the amount of the phenyl group is 42 mole %.
Comparative Example 1
[0094] 100 parts by mass of mixture A obtained in Preparation
Example 1, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
part by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, and 0.15 part by mass of (D)
benzotriazole were added and mixed by a two-roll mill. Further, 0.6
part by mass of (E) dicumyl peroxide was added as a curing agent
and mixed by the two-roll mill to prepare silicone composition 7.
Silicone composition 7 was molded and cured according to the
aforesaid methods so as to prepare cured rubber products. The
properties of the cured products were evaluated. The results are as
shown in Table 1.
Comparative Example 2
[0095] 100 parts by mass of mixture A obtained in Preparation
Example 1, 0.1 part by mass of a solution of chloroplatinic acid
hexahydrate in 2-ethylhexanol, containing 2 mass % of platinum, 0.1
part by mass of carbon black, 5.0 parts by mass of titanium oxide,
0.5 part by mass of cerium oxide, 0.15 part by mass of (D)
benzotriazole and 1 part by mass of (F') silicone oil which is
represented by the following formula and had 27% of a phenyl group,
based on the total number of the substituents were added and mixed
by a two-roll mill. Further, 0.6 part by mass of (E) dicumyl
peroxide was added as a curing agent and mixed by the two-roll mill
to prepare silicone composition 8. Silicone composition 8 was
molded and cured according to the aforesaid methods so as to
prepare cured rubber products. The properties of the cured products
were evaluated. The results are as shown in Table 1.
##STR00015##
wherein the amount of the phenyl group is 27 mole %.
Comparative Example 3
[0096] 100 parts by mass of mixture A, 0.1 part by mass of a
solution of chloroplatinic acid hexahydrate in 2-ethylhexanol,
containing 2 mass % of platinum, 0.1 part by mass of carbon black,
5.0 parts by mass of titanium oxide, 0.5 part by mass of cerium
oxide, 0.15 part by mass of (D) benzotriazole and 1 part by mass of
(F') silicone oil which is represented by the following formula and
had 39% of a phenyl group, based on the total number of the
substituents were added and mixed by a two-roll mill. Further, 0.6
part by mass of (E) dicumyl peroxide was added as a curing agent
and mixed by the two-roll mill to prepare silicone composition 9.
Silicone composition 9 was molded and cured according to the
aforesaid methods so as to prepare cured rubber products. The
properties of the cured products were evaluated. The results are as
shown in Table 1.
##STR00016##
wherein the amount of the phenyl group is 39 mole %.
Comparative Example 4
[0097] 100 parts by mass of mixture A, 0.1 part by mass of a
solution of chloroplatinic acid hexahydrate in 2-ethylhexanol,
containing 2 mass % of platinum, 0.1 part by mass of carbon black,
5.0 parts by mass of titanium oxide, 0.5 part by mass of cerium
oxide, 0.15 part by mass of (D) benzotriazole and 1 part by mass of
(F') silicone oil which is represented by the following formula and
had 47% of a phenyl group, based on the total number of the
substituents were added and mixed by a two-roll mill. Further, 0.6
part by mass of (E) dicumyl peroxide was added as a curing agent
and mixed by the two-roll mill to prepare silicone composition 10.
The silicone composition was molded and cured according to the
aforesaid methods so as to prepare cured rubber products. The
properties of the cured products were evaluated. The results are as
shown in Table 1.
##STR00017##
Comparative Example 5
[0098] 100 parts by mass of mixture A, 0.1 parts by mass of carbon
black, 5.0 parts by mass of titanium oxide, 0.5 part by mass of
cerium oxide, 0.15 part by mass of (D) benzotriazole and 1 part by
mass of (F) silicone oil which is represented by the following
formula and had 44% of a phenyl group, based on the total number of
the substituents were added and mixed by a two-roll mill. Further,
0.6 part by mass of (E) dicumyl peroxide was added as a curing
agent and mixed by the two-roll mill to prepare silicone
composition 11. Silicone composition 11 was molded and cured
according to the aforesaid methods so as to prepare cured rubber
products. The properties of the cured products were evaluated. The
results are as shown in Table 1.
##STR00018##
wherein the amount of the phenyl group is 44 mole %.
Comparative Example 6
[0099] 100 parts by mass of mixture D obtained in preparation 4,
0.1 part by mass of a solution of chloroplatinic acid hexahydrate
in 2-ethylhexanol, containing 2 mass % of platinum, 0.1 part by
mass of carbon black, 5.0 parts by mass of titanium oxide, and 0.5
part by mass of cerium oxide, and 1 part by mass of (F) silicone
oil which is represented by the following formula and had 44% of a
phenyl group, based on the total number of the substituents were
added and mixed by a two-roll mill. Further, 0.6 part by mass of
(E) dicumyl peroxide was added as a curing agent and mixed by the
two-roll mill to prepare silicone composition 12. Silicone
composition 12 was molded and cured according to the aforesaid
methods so as to prepare cured rubber products. The properties of
the cured product were evaluated. The results are as shown in Table
1.
##STR00019##
wherein the amount of the phenyl group is 44 mole %.
TABLE-US-00001 TABLE 1 Ex. Ex. Ex. Ex. Ex. Ex. Com. Com. Com. Com.
Com. Com. 1 2 3 4 5 6 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
Composition No. 1 2 3 4 5 6 7 8 9 10 11 12 Hardness 60 59 59 58 56
64 61 60 58 59 60 60 Tensile strength, MPa 9.2 9.1 9.2 9.1 8.1 8.2
9.1 8.9 8.9 8.7 8.9 9.1 Elongation at break, % 700 690 700 650 850
600 680 690 710 720 690 690 Tear strength, kN/m 39 39 38 41 31 30
35 38 34 35 35 36 Tensile permanent strain, % 8.2 7.8 7.9 3.2 10.2
10.5 8.1 7.8 8.3 8.5 8.3 7.9 The minimum destruction time, 360<
360< 360< 360< 360< 360< 48 360< 360< 360<
25 220 min The number of the test sheet 0/5 0/5 0/5 0/5 0/5 0/5 5/5
2/5 4/5 4/5 5/5 5/5 having the through hole/ Total number of the
sheets The maximum erosion depth, mm, 4.0 3.9 4.2 4.0 4.6 4.0 5.8
5.8 5.8 5.8 5.8 5.8 Evaluation Good Good Good Good Good Good Bad
Bad Bad Bad Bad Bad The average weight loss, % 0.94 0.67 0.99 0.79
1.04 0.80 9.41 1.33 7.20 6.71 15.00 9.20 Evaluation Good Good Good
Good Good Good Bad Poor Bad Bad Bad Bad Tracking test Pass Pass
Pass Pass Pass Pass Fail Pass Pass Pass Fail Fail
[0100] As shown in Table 1 above, the cured products obtained from
the compositions which do not contain component (C), (D) or (F) had
poor tracking resistance (Comparative Examples 1, 5 and 6).
[0101] Further, the compositions of Comparative Examples 2 and 3
which comprised the organopolysiloxane having the smaller amount of
the aromatic hydrocarbon groups in place of the present component
(F) and the composition of Comparative Example 4 which comprised
the organopolysiloxane having the excessive amount of the aromatic
hydrocarbon groups in place of the present component (F) provided
the cured products having good tracking resistance, but the erosion
depth was somewhat large and the progress of the breakdown of the
sheet was not prevented.
[0102] In contrast, the cured products obtained by curing the
present silicone compositions had the small tensile permanent
strains and were excellent in the mechanical strength such as
tensile strength and tear strength. Furthermore, they were superior
in tracking resistance and the progress of erosion was prevented.
These results show that the present silicone composition has
excellent high-voltage electrical insulation properties.
[0103] The cured product obtained by curing the present silicone
composition is suitable for use in power cable connection and is
useful as a material for connecting a power cable.
* * * * *